Park Report

Dassen Island Nature Reserve

NDVI and Time Since Fire

Figure 1. Leaflet map showing delta NDVI, NDVI, number of years since the most recent fire, and recent invasive species records. NA values in the delta NDVI and NDVI layers indicate missing data (e.g. due to clouds, water, etc.). Delta NDVI is the difference between observed NDVI and expected NDVI (i.e., the long-term mean). Monthly delta NDVI is calculated relative to the mean NDVI of the current month across the MODIS record while long-term delta NDVI is calculated relative the mean NDVI across the entire MODIS record. NA values in the delta NDVI layer indicate missing data (e.g. due to clouds, water, etc.). NDVI data are from 2025-01-17. NA values in the fire layer indicate that no fires have been recorded for that area. Note that the color scale for fires has been truncated, and any sites with more than 20 years since fire appear as 20. The number of years since fire can be seen by hovering your cursor over the polygon of interest. Vegetation age polygons for the park are available at: #r park_fires_file. A raster layer of vegetation age (years since fire) is available at https://github.com/AdamWilsonLab/emma_report/releases/download/current/years_since_fire.tif .The mean current NDVI layer is available at https://github.com/AdamWilsonLab/emma_envdata/releases/download/current/mean_ndvi.tif .

Area burned and vegetation ages

Figure 2. Top: Total area burned each year in the park. Bottom: Ridgeplot histogram showing vegetation age distributions within the park over time. Percentages shown represent amount of vegetation that is 20 years old or older. Note that areas where fires are not known to have occurred have been assigned a vegetation age of 20 years.

Weather Data

Figure 4. Climate Data from GSOD. Mean data is a long-term average for each day of the year across these weather stations.

Figure 5. Climate Data from GSOD. Mean data is a long-term average for each day of the year across these weather stations.

Drought Indices

SPI

The Standardized Precipitation Index (SPI) is a drought index ranging from -3 (very dry) to +3 (very wet).

Report Metadata

This table summarizes the date this report was generated and the most recent observation for each data type.

Description	Date last updated
Website	2025-May-21
NDVI	2025-Jan-17
Weather	2025-May-17